1. Field of the Invention
The present invention relates to a method of making oxygenates, particularly a method of making oxygenates from a non-catalytic chemical reaction.
2. Description of the Prior Art
Natural gas is an abundant fossil fuel resource. The composition of natural gas at the wellhead varies but the majority of the hydrocarbon contained in the natural gas is methane. Other constituents of natural gas may include ethane, propane, butanes, pentane, and heavier hydrocarbons.
A reaction which has been extensively studied for many years is the direct partial oxidation reaction of the hydrocarbons in natural gas, particularly methane and ethane, to oxygenates, e.g. methanol, and ethanol, however, care must be taken to avoid oxidation to formaldehyde or other undesirable deep oxidation reactions including CO and CO2. The mechanism of alcohol formation is believed to involve a radical reaction, e.g. methyl free radicals and hydroxyl free radicals. Unfortunately, the per pass yield to valuable oxygenates has been limited, making these systems uneconomical. This limited yield has been rationalized as resulting from the low reactivity of C—H bonds in the hydrocarbons, e.g., methane, in relation to the higher reactivity of the primary oxygenated product, e.g. methanol, which results in selectivity formation of the highly undesirable deep oxidation products CO and CO2 when attempts are made to increase conversion.
A variety of reaction systems and methods for conversion of hydrocarbons to desirable oxygenates through direct partial oxidation of the hydrocarbons are known; however each of those reaction systems has significant problems that have prevented these systems from being used to recover gas at location where it would normally be flared due to lack of infrastructure to capture the natural gas. Since the direct partial oxidation reaction of hydrocarbons to oxygenates is exothermic in nature, tubular reactors that carry out the direct partial oxidation reaction often develop “hot spots” and are difficult to efficiently control. Accordingly, it is very problematic to keep the reaction temperature constant inside the reactor. In addition, since the direct partial oxidation reaction of hydrocarbons to oxygenates is a gas phase reaction, heat integration between gas reactants and gas products require gas to gas heat exchange. Gas to gas heat exchange is notoriously inefficient because there are infrequent collisions between the gas particles and the walls of the heat exchanger. Therefore, for direct partial oxidation reaction of hydrocarbons to oxygenates, heat transfer becomes a limiting factor in process design. The implementation of hydrocarbon gas conversion has been limited to complex plants with substantial infrastructure and controls, which are not possible in remote locations.